Semiconductor technology pervades most electronic devices today. Computers, televisions, videocassette recorders, cameras, etc., all use semiconductor integrated circuits to varying degrees. For example, the typical computer includes microprocessors and dedicated controller integrated circuits (i.e., video controllers, audio controllers, etc.), as well as memory, such as dynamic random-access memory.
Traditionally, the semiconductor industry has used a process that requires first building a device or series of devices, and then connecting the devices together with a wiring level or levels above the active-device surfaces. As integrated circuit designs have become more complex, several external wiring planes have been used to connect adjacent devices. As the number of wiring levels grew, the requirement of the vertical connections has significantly reduced the usefulness of the lower levels.
A limited prior art solution is to use a single buried wiring level in the initial phases of semiconductor fabrication. A single buried wiring level overcomes the limitations of using external wiring planes, but is not entirely applicable to current semiconductor technology. For example, stacked chip arrays require more than one wiring level. Therefore, even if a single buried wiring level is used, external wiring planes are still nevertheless required.
For these and other reasons, there is a need for multiple buried wiring levels within a single semiconductor device or structure.